I'm stretching the timeline here, so think of this piece as canon but somewhat AU – otherwise the notion of a Halloween party in the spring (I'm assuming that's when the late Season 7 takes place) becomes an X File in itself. Also let's admit it, M&S as a couple should have gotten way more screen time than it did.

Keeping Us Between Us

Part One: The Purple Blouse

She first learned of its existence when a notice landed in her work inbox. Each year on Halloween, there was a dance for the HQ employees in a fancy hotel in town, with some theme or other. It was a tradition she'd heard about since her early days in Quantico; nonetheless, those evenings had never quite held her interest. In all her years at the FBI she attended only one dance, her first year at the Academy, and even then she got bored about an hour later. Then she was assigned to the X Files and her life changed from end to end. It so happened they were always on the road around the time the dance was to take place. Several years into her assignment to the X Files she discovered Mulder was doing this on purpose – he loathed social engagements of any sort and had always done everything in his power to steer clear of them. She discovered that the hard way once, when they got stuck in a forest in North Florida on their way to a teamwork seminar, searching for Moth Men.

But this year, everything was different. She was determined to go to that dance. According to the email she received, the theme was going to be the 50s, and she absolutely loved that idea. She remembered how she and Melissa used to dress like the characters in Grease when the movie came out, reenacting scenes and songs much to their parents' dismay. Not slutty Sandy; they had never liked that plot twist. Dresses in various pastel colors with their tight waists and billowing skirts suited them just fine. They were always a few sizes too big for them, having come from goodwill stores or some relative or other, but they didn't care, spent hours flaunting them anyway.

And there was another reason she wanted to go to the dance. For the first time in she didn't know how long, she actually had a potential date for it. The trick would be how to ask him. She knew that over the years, Mulder's opinion hadn't changed, that his aversion of their peers quite possibly even intensified. But he'd made it pretty clear that there was very little he would deny her. And maybe, just maybe, if she asked nicely enough, he would relent. Either way it was worth a shot, and she enjoyed a good challenge.

And so upon receiving the email, she forwarded it to him with the word "please?" in the title. She knew he had probably received a copy of his own, but knowing him, he would ignore it as soon as he saw it. An email directly from her would be harder to ignore. He wasn't due at the office until noon the following day, having been called for a consultation on a crime scene downtown, and so she had plenty of time to carefully lay out her strategy. The next morning she wore a new blouse, dark purple, the top button of which – once in the safety of their basement office – she had undone. She rolled the sleeves up her elbows, ready for battle. Luckily she had enough work to do to distract her from the mission ahead, and so she delved into her pile of field reports and forgot all about it. By the time Mulder arrived she was dizzy with information, and her shoulders were protesting against her hunched position over her desk.

"Hey, you," he said as he walked in, flashing a secret smile at her before turning to shut the door. Clearly taking advantage on her drowsy state, he dropped a kiss on the top of her head before she had a chance to remind him they're at work. "Coffee?" he asked, and she suddenly noticed the two cups in a carrier he had left by the door.

"Oh my God, yes," she all but leaped out of her chair. He chuckled at her enthusiasm as he handed her one of the cups. Just the smell of it made her head spin. She closed her eyes and sniffed. "It's like you read my mind, thank you."

"Hmm... Wanna check if you can read mine?"

She opened her eyes a crack to find his suggestive smile as he inched closer. "Mulder..." she warned him, taking a step back.

"Party pooper," he scoffed, but there was this teasing glint in his eyes. "You do know most people in this building already think we're sleeping together, right? Probably since week two, when you didn't run off screaming after our first case."

"Do you include AD Skinner in people?" Honestly, she didn't give these matters too much thought. Being a woman in a men's world had forced her to develop a thicker skin, an immunity to gossip. But he clearly had been paying close attention to the rumor mill. She assumed he probably couldn't help it, being a profiler, an occupational hazard of sorts. She looked at him expectantly, her curiosity getting the better of her. He was grinning mischievously, which she interpreted as affirmation. "Really? How can you tell?"

"Maybe I can read his mind, too," he deadpanned. She raised an eyebrow at him. "Sometimes when we're in his office he looks at us like... he's expecting us to pounce on each other any second."

She chuckled at the mental image, but was too embarrassed to admit to him it was most likely the case, as far as she was concerned, even before they happened. She cleared her throat, steering her thoughts back to the right track. "Well, be that as it may, I rather we keep us between us for the time being, okay?"

He raised his arms in mock-surrender, then turned to his desk with no further argument. That reminded her of the plan ahead; coffee and banter had her sidetracked for a second there. Returning to her seat, she sipped her coffee slowly and willed her mind into focus. From the corner of her eye she could see him unlock his computer, type in his password. She had to remain inconspicuous. She grabbed another case file from her thinning pile, but her concentration was gone. She looked down anyway, pretending to inspect it. She heard a few clicks, then a sound that was half a chuckle, half a scoff.

"What are you playing at?"

She raised her head at the question and met his gaze. "I'm sorry?"

"I wasn't born yesterday, Scully." She tilted her head in reply, pulling on her best innocent face, not wishing to give him any indication she knew what he was talking about. He rolled his eyes at her, obviously not buying it. "Your email, Scully? About the Halloween dance?" She could tell by the look on his face he knew exactly what this was about, and her cheeks flushed with wordless admission. He shook his head defiantly. "I'm not going."

"Come on, Mulder, please? Just this once would you please get over this anthrophobia of yours?"

"Not a chance in hell. Besides, what happened to keeping us between us?"

"That's different."

"Not that different."

"In the seven years we've been working together, we've always done things your way and I accepted it without question. Autopsies in the middle of the night, getting ditched repeatedly during field work, and I cannot possibly stress that enough, the Flukeman? You owe me, Mulder."

At least he had the courtesy to appear guilty. For a second, that is. "There's nothing I wouldn't do for you, Scully. You know that. But I draw my line at work parties. They make me feel self-conscious. I don't need to give people more reasons to be talking behind my back. Don't we see the lot of them enough on a daily basis that I'm expected to socialize with them out of hours as well?"

"Actually no, Mulder, we don't see the lot of them, as we're stuck down here most of the day, or out in the field investigating one oddity or other. A tiny bit of socializing won't kill you. If anything, you'll only gain from it."

"A headache is about the only thing I could gain from it," he backfired, then shook his head a bit warily. "Look, I know what you're trying to do here."

She leaned back in her seat and sneered at him. "Are you profiling me, Agent Mulder?"

"I don't need to, I read you like a book. You wouldn't wear a blouse like that to work unless you mean to get something by it."

She kept her expression sealed, not admitting it but not denying it either. But she couldn't help asking. "Is it working?"

"You look gorgeous, and this blouse is too delicious for its own good, but I'm onto you. I won't fall for cheap ploys. Forget it. I'm not going. Case closed."

She had anticipated his fierce resistance, so she wasn't intimidated exactly. But seeing as she wasn't getting anywhere, it seemed the right time to launch Plan B. "Okay, fine," she told him. "I guess I'll call James and tell him I'm free after all," she added as an afterthought.

That got his attention alright. He froze for just a moment. "Who?" he all but growled.

"James. Agent Larson. You know, the newbie at the forensic lab. Funny guy, chocolate skin, gorgeous smile. I met him in the elevator the other day and he asked if I wanted to go to that dance with him."

He looked at her for a long moment. Familiar with his interrogation techniques, she held his gaze without faltering. Eventually he shook his head. "You're bluffing." There was the slightest quiver in his voice, a flash of doubt in his hazel eyes, both of which made his argument a little less convincing.

"You'd think I have better things to do with my time than bluff," she said in mock-offense. He kept his eyes on her as if he was expecting her to cave, but she wasn't going to. She was on a roll. "To the best of my knowledge, we never said we were exclusive," she added coolly. She could see her words stung. In fact, he looked so miserable that for a second she wanted to take it back and forget about the whole thing, but quickly decided against it. It would be worth it. "Funny. You'd believe just about anything, but not this. How about I'll give him a call right now and prove it to you?"

Her heart pounded as she reached for the phone. She hoped the rest of her plan wouldn't crumble if she actually had to call the dashing but clueless Agent Larson. Thankfully Mulder was by her side in half a second, his hand covering hers, in full-on alpha male mode. She looked up at him questionably. He narrowed his eyes at her as if he knew exactly what she was up to.

"Fine. You win. We'll do this your way." She kept looking at him, eyebrow raised. He sighed with exasperation, knowing what she'd been waiting for. "I'll go with you to the dance, goddamnit."

She struggled contain her enthusiasm, but felt it bubbling to the surface. She couldn't stop a smile from escaping. Mission accomplished. She stood up and grabbed his tie. The motion was so sudden that he lost his balance, toppled forward, and they slammed into the file cabinet behind her, moans of pain melting into breathless giggles. Catching their breaths, they gazed at one another for a second with mutual intention, the fire in his eyes a perfect reflection of the one already consuming her. As his fingers grazed the blouse button she had previously undone, she thought she should probably rebuff him, say something about prudence or decorum, but then his lips came crushing against hers and her resistance was deemed futile.

After all, nobody down there but the FBI's most unwanted.